本文基于中国4省份397个生猪养殖户调查数据,引入损害控制模型(damage control model),分析了生猪养殖户使用兽药的边际生产率。本文建立兽药使用的回归模型,将由此回归模型得到的兽药使用成本预测值代入Cobb-Douglas生产函数及损害控...本文基于中国4省份397个生猪养殖户调查数据,引入损害控制模型(damage control model),分析了生猪养殖户使用兽药的边际生产率。本文建立兽药使用的回归模型,将由此回归模型得到的兽药使用成本预测值代入Cobb-Douglas生产函数及损害控制模型以处理内生性,所得回归分析结果显示:病害预期损失、兽药平均价格以及养殖规模对兽药使用成本具有显著的正向影响;对不同类型兽药的使用成本而言,养殖监管水平、参与养殖技术培训情况以及养殖信息获取便捷程度对保健类兽药的使用成本具有显著的负向影响,而对治疗类兽药的使用成本并无显著影响;对于治疗类兽药来说,损失厌恶是导致其使用成本上升的主要原因,其他相关因素影响较小。此外,根据损害控制模型的估计结果,本文发现,兽药的边际生产率接近于0,表明所调查地区生猪养殖户已经过量使用兽药。展开更多
To model the damage process of masonry walls under blast loading, a dynamic continuum damage material model is constructed for brick and mortar separately. The degradation of both the stiffness and strength are govern...To model the damage process of masonry walls under blast loading, a dynamic continuum damage material model is constructed for brick and mortar separately. The degradation of both the stiffness and strength are governed by a damage variable. By using the proposed material model, damage and fragmentation of a typical masonry wall under blast loading at different scaled distances is calculated. The hazard level of the masonry wall to blast loading is evaluated by analyzing the numerical results.展开更多
AIM: To investigate the effectiveness of 4 d' anti-Helicobacter pylori therapy on the H pylori-infected Mongolian gerbils based on physiological and pathological changes. METHODS: We used 6-wk-old male gerbils ora...AIM: To investigate the effectiveness of 4 d' anti-Helicobacter pylori therapy on the H pylori-infected Mongolian gerbils based on physiological and pathological changes. METHODS: We used 6-wk-old male gerbils orally inoculated with H pylori (ATCC43504, 2×108 CFU/mL). Seven weeks after H pylori inoculation, the animals of study group received 4 d' anti-H pylori triple therapy (H pylori-eradicated group). Seven days later, all animals of the H pylori-eradicated and control groups (H pylori-infected & H pylori-uninfected groups) were sacrificed. We examined gastric mucosal lesions macroscopically, studied gastritis microscopically and determined the stomach weight ratio, myeloperoxidase (MPO) activity and prostaglandin (PG) E2 level. RESULTS: The results showed that both macroscopic and histological gastric damages were significantly less in H pylori-eradicated group than H pylori-infected group. Stomach weight ratio, MPO activity and PGE2 levels were significantly higher in H pylori-infected group than those in the other two groups. CONCLUSION: Four days' anti-H pylori therapy was effective in the improvement of H pylori-induced gastric lesions in Mongolian gerbils.展开更多
Rats have been the primary model to study the process and underlying mechanisms of recovery after spinal cord injury. Two weeks after a severe spinal cord contusion, rats can regain weight-bearing abilities without th...Rats have been the primary model to study the process and underlying mechanisms of recovery after spinal cord injury. Two weeks after a severe spinal cord contusion, rats can regain weight-bearing abilities without therapeutic interventions, as assessed by the Basso, Beattie and Bresnahan locomotor scale. However, many human patients suffer from permanent loss of motor function following spinal cord injury. While rats are the most understood animal model, major differences in sensorimotor pathways between quadrupeds and bipeds need to be considered. Understanding the major differences between the sensorimotor pathways of rats, non-human primates, and humans is a start to improving targets for treatments of human spinal cord injury. This review will discuss the neuroplasticity of the brain and spinal cord after spinal cord injury in rats, non-human primates, and humans. A brief overview of emerging interventions to induce plasticity in humans with spinal cord injury will also be discussed.展开更多
Peripheral nerves are particularly vulnerable to injuries and are involved in numerous pathologies for which specific treatments are lacking. This review summarizes the pathophysiological features of the most common t...Peripheral nerves are particularly vulnerable to injuries and are involved in numerous pathologies for which specific treatments are lacking. This review summarizes the pathophysiological features of the most common traumatic nerve injury in humans and the different animal models used in nerve regeneration studies. ~Ihe current knowledge concerning Wallerian degeneration and nerve regrowth is then described. Finally, the involvement of intraneural vascularization in these processes is addressed. As intraneural vascularization has been poorly studied, histological experiments were carried out from rat sciatic nerves damaged by a glycerol injection. The results, taken together with the data from literature, suggest that revascularization plays an important role in peripheral nerve regeneration and must therefore be studied more carefully.展开更多
a damage constitutive model comprising two dynamite sticks is established and handled with the transient dynamics finite element computer program PRONTO-3D to study rock damage and fragmentation during blasting. Simul...a damage constitutive model comprising two dynamite sticks is established and handled with the transient dynamics finite element computer program PRONTO-3D to study rock damage and fragmentation during blasting. Simulation tests find that tensile stress by detonation gives rise to tensile bulk strain and consequently damage in the material. Maximum bulk strain is observed in simultaneous detonations of the two dynamite sticks. It is demonstrated that the proposed method is applicable to studying the process of rock damage by blasting as well as its affecting factors.展开更多
文摘本文基于中国4省份397个生猪养殖户调查数据,引入损害控制模型(damage control model),分析了生猪养殖户使用兽药的边际生产率。本文建立兽药使用的回归模型,将由此回归模型得到的兽药使用成本预测值代入Cobb-Douglas生产函数及损害控制模型以处理内生性,所得回归分析结果显示:病害预期损失、兽药平均价格以及养殖规模对兽药使用成本具有显著的正向影响;对不同类型兽药的使用成本而言,养殖监管水平、参与养殖技术培训情况以及养殖信息获取便捷程度对保健类兽药的使用成本具有显著的负向影响,而对治疗类兽药的使用成本并无显著影响;对于治疗类兽药来说,损失厌恶是导致其使用成本上升的主要原因,其他相关因素影响较小。此外,根据损害控制模型的估计结果,本文发现,兽药的边际生产率接近于0,表明所调查地区生猪养殖户已经过量使用兽药。
文摘To model the damage process of masonry walls under blast loading, a dynamic continuum damage material model is constructed for brick and mortar separately. The degradation of both the stiffness and strength are governed by a damage variable. By using the proposed material model, damage and fragmentation of a typical masonry wall under blast loading at different scaled distances is calculated. The hazard level of the masonry wall to blast loading is evaluated by analyzing the numerical results.
文摘AIM: To investigate the effectiveness of 4 d' anti-Helicobacter pylori therapy on the H pylori-infected Mongolian gerbils based on physiological and pathological changes. METHODS: We used 6-wk-old male gerbils orally inoculated with H pylori (ATCC43504, 2×108 CFU/mL). Seven weeks after H pylori inoculation, the animals of study group received 4 d' anti-H pylori triple therapy (H pylori-eradicated group). Seven days later, all animals of the H pylori-eradicated and control groups (H pylori-infected & H pylori-uninfected groups) were sacrificed. We examined gastric mucosal lesions macroscopically, studied gastritis microscopically and determined the stomach weight ratio, myeloperoxidase (MPO) activity and prostaglandin (PG) E2 level. RESULTS: The results showed that both macroscopic and histological gastric damages were significantly less in H pylori-eradicated group than H pylori-infected group. Stomach weight ratio, MPO activity and PGE2 levels were significantly higher in H pylori-infected group than those in the other two groups. CONCLUSION: Four days' anti-H pylori therapy was effective in the improvement of H pylori-induced gastric lesions in Mongolian gerbils.
文摘Rats have been the primary model to study the process and underlying mechanisms of recovery after spinal cord injury. Two weeks after a severe spinal cord contusion, rats can regain weight-bearing abilities without therapeutic interventions, as assessed by the Basso, Beattie and Bresnahan locomotor scale. However, many human patients suffer from permanent loss of motor function following spinal cord injury. While rats are the most understood animal model, major differences in sensorimotor pathways between quadrupeds and bipeds need to be considered. Understanding the major differences between the sensorimotor pathways of rats, non-human primates, and humans is a start to improving targets for treatments of human spinal cord injury. This review will discuss the neuroplasticity of the brain and spinal cord after spinal cord injury in rats, non-human primates, and humans. A brief overview of emerging interventions to induce plasticity in humans with spinal cord injury will also be discussed.
基金supported by a doctoral fellowship from the ‘Conseil Régional du Limousin’ to MC
文摘Peripheral nerves are particularly vulnerable to injuries and are involved in numerous pathologies for which specific treatments are lacking. This review summarizes the pathophysiological features of the most common traumatic nerve injury in humans and the different animal models used in nerve regeneration studies. ~Ihe current knowledge concerning Wallerian degeneration and nerve regrowth is then described. Finally, the involvement of intraneural vascularization in these processes is addressed. As intraneural vascularization has been poorly studied, histological experiments were carried out from rat sciatic nerves damaged by a glycerol injection. The results, taken together with the data from literature, suggest that revascularization plays an important role in peripheral nerve regeneration and must therefore be studied more carefully.
基金Chongqing Yudong Freeway Engineering Co.Ltd. (SJ-43-0106191)Chongqing Traffic Committee ([2002]23-3#) and Henan Province Preeminent Youth Foundation (0310053100).
文摘a damage constitutive model comprising two dynamite sticks is established and handled with the transient dynamics finite element computer program PRONTO-3D to study rock damage and fragmentation during blasting. Simulation tests find that tensile stress by detonation gives rise to tensile bulk strain and consequently damage in the material. Maximum bulk strain is observed in simultaneous detonations of the two dynamite sticks. It is demonstrated that the proposed method is applicable to studying the process of rock damage by blasting as well as its affecting factors.
